Spiral Wound Gaskets - Acidic Oxygen Service

Gents+1

an autoclave that I have "inherited" has oxygen injection lines which oxidise sulphide ore slurry; releasing heat and forming acid. The object is to shatter quartz encapsulation of gold particles in the slurry by thermal shock and chemical attack thereby improving downstream cyanide leach recovery ($$$). It works. Temperatures are around 250C and pressures around 31 bar. I think the internal (hot)oxy injection lines are Ferallium (havent had time to find out) and (cold) external lines are stainless; probably 316.But much of the wet area pipework is titanium, for corrosion resistance. Titanium + oxygen is normally a no-no as Ti can burn in oxygen. Ferallium doesnt burn but is becoming difficult to source.
Flanges on the autoclave are Ti spiral wound. This is OK because the oxy concentrations are fairly low and can be adjusted by partial pressure regulation.
The external 36 bar(cold)oxy lines are flanged (typically 50NB) with fawn (I think) Gylon gaskets which appear to have held up well (4 years).
However it has been suggested replacing with spiral wound gaskets and I cant see the point. Presumably the flange faces would need to be ground, and I expect a spiral wound gasket would not be as forgiving as Gylon when it comes to alignment and torquing.

The question is: what advantage would there be in changing from Gylon to spiral wound, given successful operating experience with the former?

Personally I can only see disadvantages, but feel I may be missing something.

Your conjecture/experience would be appreciated.

Cheers

Steve Received on Thu Sep 09 04:35:00 2004